The use of vertical water wells as a thermal source/sink for efficient ground source heat pump operation has been in use since the 1980s. An often-specified energy conservation system today is a closed loop system that employs pipes, such as polypipes, grouted into the bore of the wall. These grouted loop (GL) systems operate with a secondary heat transfer fluid between the well bore and the heat pump heat exchanger. While GL closed loop systems offer relatively low maintenance over the lifetime of the installation, the high initial cost of the well field is a handicap to universal acceptance.
Open loop systems, on the other hand, operate as traditional water wells. In such systems, each well requires its own pump, which at some point will require replacement. The benefit of open loop systems, however, is that they maximize heat transfer to the well bore rock, particularly where the entire length of the well is used in the heat exchange, a mechanism described in U.S. Pat. No. 5,183,100, incorporated herein. Because of this improved heat transfer, open loop systems require typically half the number of wells drilled as do closed loop systems. This translates into significant initial savings to the owner.
A standing column well (SCW) is particularly suited to open loop systems and the lower-cost benefits thereof, but closed systems are also contemplated herein. Typically, a standing column well is used as both a heat transfer system and a supply well, where the well production permits. With sufficient water flow, the water production, or bleed, of a standing column well may be 10-30% or more of the amount used. However, even with some water taken from the standing column well as supply water, a large volume of water is constantly returned to the standing column well from the heat transfer unit.
With the recent significant increases in the costs of energy, ground source heat pump (GSHP) technology systems, particularly those employing standing column well technology, have become a viable option for heating and cooling of buildings, even more efficient than gas or oil fired furnaces and boilers. Nonetheless, the initial cost of a complete GSHP system installation, drilling, deployment and equipment, has been a hurdle to more significant market penetration of this energy alternative. In the last decade, however, the annual operational cost savings of GSHP technology has demonstrated payback opportunities of 5-7 years. With the more recent escalation of fuel prices, payback time is now typically 3-5 years. However, in order to expand the use of GSHP technology even further, there remains a need to reduce the deployment and installation costs of GSHP systems, making these energy-conservation systems even more economically attractive.
Therefore, there is a need for an improved return water system and installation methodologies that provide an optimal, low cost solution for ground water heat transfer systems for use by individuals and institutions desirous to save costs in energy conservation.
Furthermore, in this time of need for alternative energy sources to fossil fuels and the desire to prevent further harm to the environment, such as contributing to green house gas and other deleterious environmental hazards, there is a need for an environmentally-friendly, clean, self-renewing, non-toxic, and convenient system to provide basic heating and cooling needs for individuals and institutions.